Tele Vue-NP127is Operating Guide

Tele Vue®
Operating Guide
660mm f/5.2 IMAGING SYSTEM
4-ELEMENT APO REFRACTOR
Thank you for purchasing the Tele Vue-NP127is. It has been our pleasure to craft this fine instrument for you.
Nearly thirty years ago, Al Nagler received a U.S. patent for a fast, refracting telescope design based on
Josef Petzval’s portrait camera lens concept. Petzval’s design uses widely spaced doublets to produce a
flat focal plane over a relatively narrow field of view, just the sort of field a fast telescope can see. Nagler’s
combination of flat-field, fast focal ratio, and unobstructed system lent itself perfectly for testing eyepieces.
The 5” f/4 MPT (Multi-Purpose Telescope) with its fast speed and wide, flat field, led to a series of
continuous improvements, primarily in color correction. The “Halley Commemorative,” 4” f/5.5 started
the parade where more advanced glasses including special dispersion, fluorite and fluorite substitute
glasses brought steady improvements. The 4” f/5 Genesis employed fluorite in the rear doublet, and the
subsequent SDF and Tele Vue-101 versions at f/5.4 brought us even closer to perfection. Maintaining
this fast f/5.4 speed while reducing tube length in a totally new design with new glasses allowed virtually
ideal color correction and improved field flatness in this, the ideal form culminating the 20 year refinement
toward perfection with the Nagler-Petzval 101, and NP127 with an even faster f/5.2 speed.
The Tele Vue-NP127is refines the original NP127 with the addition of a more robust, larger focuser
now standard with 10:1 reduction. The “is” designation denotes Imaging System, Tele Vue telescopes
with specific mechanical advantages for photography. Tele Vue offers a series of accessories in conjunction with each optical system so you are assured of compatibility and maximum performance. While the
NP127is maintains all the visual prowess of the previous NP127, the larger rear elements and larger
focuser along with a host of proprietary Imaging System accessories, make it ideally suited for the CCD
imager.
WARNING: NEVER try to look at the sun or point the telescope toward or near the sun without
professional solar observing equipment rigidly secured in front of the objective lens. When
observing the sun with the proper filters,
remove any sighting devices such as Star- 2” Accessory Adapter (left)
Imaging System Adapter (right)
beam from the telescope. Use only the Tele Vue Sol
Searcher to find the sun. Instant and permanent eye
Optical Tube Assembly
damage may result from viewing the sun directly, even
during a solar eclipse, or when viewing through thin
clouds, or when the sun is near the horizon.
Lens Cap
Standard Features - Optical tube assembly includes:
captive sliding dew shield, 2.4” focuser with Focusmate 10:1 reduction, tilt adjustment end ring, screwon metal lens cover, 2” Accessory Adapter, Imaging
System Adapter, custom hard-shell case, Allen Keys
for end ring tilt adjustment.
®
Tele Vue
Vi s i o n a r y
Case
1
32 Elkay Dr., Chester, New York 10918 (845) 469-4551.
televue.com
1.0 Getting Acquainted with the Tele Vue-NP127is
Focuser Body
Draw Tube Tension
Draw Tube
Main Tube
Rear Lens Cell
127mm Front
Lenses and Cell
Lock Knob
End Ring
Fine Focus
Focuser Pinion Assembly
Coarse Focus
Dew Shield in
retracted position
1.1 Optical tube assembly
The NP optical design contains four elements consisting of two widely spaced, air-spaced doublet groups.
The forward group of lenses are contained in a stainless steel lens cell. The cell attaches to the main tube
via three alignment screws. The front cell is encased within the sliding dew shield. The rear doublet, making up the rest of the objective, is larger in diameter than the previous NP127 and provides additional
illumination at the edge of the field. This benefit is especially useful for large format CCD chips which
are extremely sensitive to light fall-off. The rear lens group is housed in the cell that threads between the
back of the tube and the focuser. Never stick any long objects into the focuser or you will hit the rear-most
lens surface.
1.2 Focuser
The 2.4” output side of the NP127is focuser is designed to pass all of the field rays exiting the rear elements of the objective, as the forward end of the draw tube has a 3” internal diameter. A larger focuser,
therefore, lends no additional illumination benefit.
The NP127is is shipped in its “visual” configuration. The 2” Accessory Adapter sits within the 2.4”
inside diameter of the drawtube. Thumb
Jack Screws (typical)
Digital Indicator Kit
screws pass through both the drawtube and
Mounting Points
Drawtube Tension adapter to cinch a brass clamp ring around 2”
accessories. With three thumb screws there
Screw (typical)
is enough holding power for the heaviest of
visual accessories!
Lock Screws
The two tension screws on the top of the
(typical)
focuser body can be adjusted to add resistance
Jam Screws
when using heavy equipment. These tension
(typical)
screws tighten against a brass clamp ring,
2” Accessory
which then cinches down on the Teflon sleeve
Adapter
in which the draw tube slides. For photography
it is not necessary to tighten beyond the need
to keep a camera stationary but we do recommend to tighten them in unison to avoid any
focus shift. Note that even when sufficiently
tight, the focuser knobs can still drive the draw
tube.
The end ring can be adjusted (and locked)
1:1 Knob
1:1 Knob
to compensate for any tilt effects seen in CCD
10:1 Knob
imaging. Lock screws in the end of the draw
Focuser with 2” accessory adapter in place
tube tighten against either the taper of the
2
Imaging System Adapter or brass clamp ring within the 2” Accessory Adapter.
The threaded holes on top of the focuser body accept the Digital Indicator Kit.
Operation of the rack and pinion focuser is via the 10:1 ratio Focusmate on the right side or either
of the 1:1 knobs. You might consider the optional Focusmate Driver for vibration-free focus control.
2.0 Mounting Options and Set Up
The telescope tube diameter is 5”. The dual ring MRS-5000
is suited for photography and CCD imaging with a variety
of adapter plates that can be bolted to the base plate.
The base plate also bolts to the Tele Vue Gibraltar5 Alt-Az
mount if a more travel-friendly, visual use mount is desired.
Each tube ring has two machined channels with #10-32
threaded holes for mounting accessories. A central bar
spans across the top of the two rings for added stability.
The bottom of the tube rings have ¼-20 holes to accept
mounting studs or screws. Telescope balance is achieved
by unlocking the “bat handle” screws and sliding the tube
fore or aft. Once the O.T.A. is repositioned, retighten the
bat handle screws.
MRS-5000
3.0 Visual Observing Set Up
As previously mentioned, the NP127is is shipped in its “visual” configuration. If you have removed the 2”
Accessory Adapter and would like to re-install it, loosen the three end ring lock screws sufficiently to remove
any accessory that may be in place. However, do not retract them fully into the end ring. By allowing them
to protrude into the body (note photo below), they act as locators. Looking at the 2” Accessory Adapter,
note the three grooves with holes machined 120° apart. The grooves help index the holes in the adapter
to the three thumb screw arrangement in the end ring. This will ease installation in the dark. Insert the 2”
Accessory Adapter into the end of the focuser. If
it does not go all the way in, rotate the adapter.
When the grooves in the adapter align with the
protruding screws, the adapter will seat fully into
the focuser. Tighten the three screws a few turns
Lock Screws threaded
so they enter the holes in the adapter. The lock
partially in to use as
screws will now act against the brass clamp ring
guides for inserting
in the 2” Accessory Adapter.
the 2” Accessory
Adapter.
Slip a Tele Vue 2” Everbrite diagonal into the focuser
and tighten the lock screws. You will now be able
to reach focus with any Tele Vue eyepiece.
IMPORTANT CAUTION: When replacing the
orange plastic plug into the 2” Accessory Adapter,
push it in far enough to seat. Do not use the lock
screws to clamp the plug in place as the clamp
screws will distort the brass clamp ring in the 2”
Focuser set to accept 2” Accessory Adapter
accessory adapter.
3.1 Eyepieces
With its wide, highly corrected, flat field and fast f/ratio, the NP127is puts eyepieces to the test. This
scope demonstrates the superiority of Tele Vue eyepiece performance and, with a range of 12x to 330x
(if the atmosphere allows) there is a magnification for all purposes. See chart at the end of this manual or
call Tele Vue for recommendations. In general, we suggest choosing low and medium power eyepieces
in ratios of field stop diameters. For example, factors of 1.4 or 2.0. When choosing higher power eyepieces, use ratios of magnification. (See reference chart in the “Choosing Your Eyepieces” article.)
3
3.2 Finders
We particularly recommend using the Starbeam reflex sight (part# SFT-2003), which attaches to the Tube
Rings. The case has a cutout for the Starbeam. The Quick Release Universal Finder Bracket (QFM-1008)
can hold a traditional 50mm finderscope and also attaches to the mount ring channels.
4.0 Photographic Set Up and the Tele Vue Imaging System
Tele Vue Imaging System Accessories provide solid threaded connections between components. To use
these accessories requires the insertion of the Imaging System Adapter (ISA) into the focuser. You will find
the ISA in the accessory compartment in the lid of the telescopes case. To install the ISA, first back off the
three Lock Screws far enough to pull the 2” Accessory Adapter out from the drawtube to reveal the 2.4”
diameter. Store the adapter in the accessory compartment in the case.
You will then need to back out the screws further
so their ends are flush with the inside diameter of the
End Ring. Insert the ISA and tighten the three Lock
Screws located equidistant around the end ring.
2” Accessory Adapter removed
and lock screws backed out.
Imaging System
Accessory Adapter
Visual adapter removed.
Conversion from visual (top) to imaging (bottom) configurations. Remove 2” Accessory Adapter if present
and back off the three lock screws flush with the inside
ring. Insert the Imaging System Adapter and tighten
the three lock screws.
Arrangement for imaging.
The Imaging System’s threaded accessories provide a variety of options for camera adaptation and focal
length variation. The goal of Tele Vue’s Imaging System is to let you pursue your astrophotographic passion with ease, by providing accessories designed to work together. The following summary of parts and
pictorial diagram will help you understand each part’s use and its sequence in the chain. Please note that
spacing requirements of any particular camera will need to be met by the appropriate Imaging System
spacer or combination of spacers.
4
Focuser Features
A. Large Focuser for NP101is and NP127is
Standard features (A) include:
•Drawtube with 3” entrance aperture, 2.4” exit aperture
•End-ring with tilt capability
•3-Lock knobs to secure camera equipment or 2” adapter
•Body has brass clamp ring with 2 lock knobs
•10:1 Focusmate dual speed focuser
•Indexed 2” accessory adapter with brass clamp ring
•Imaging insert threaded for imaging system components.
Accessories (optional)
B.LMK-2404/LMF-2405 Digital Indicator Kits for
Large Focuser
C.DSF-8002 2” Everbrite Star Diagonal
D.FDF-2004 Focusmate Driver electronic vari-speed
motor control.
E. LCL-1069 Large Field Corrector for optimized edge
G.AFT-1105 48mm Filter adapter
H. AD2-1110 Apogee U47 D2/Yankee Robotic
adapter
J. STL-1071 SBIG STL series adapter
K.TRG-1072 Standard T-Ring adapter
L. CWT-2070 Canon Wide T adapter
M.A2A-1107 2” Accessory adapter
O.TLA-0250 0.25” long threaded extension
P. TLB-0375 0.375” long threaded extension
Q.TLF-0040 0.040” spacer
R. TLC-0500 0.500” long threaded extension
S. TLG-0080 0.080” spacer
T. TLD-1000 1.000” long threaded extension
performance on NP101is and NP127is
F. NPR-1073 0.8X reducer
LCL-1069 Large Field Corrector
• Optimizes edge of field performance. Recommended for 35mm CCDs (43mm diagonal) and larger.
NPR-1073 – 0.8x Reducer for NP and NPis series telescopes
• Recommended for increasing field with APS size formats (27mm diagonal)
• Constructed to fit both standard 2” focuser NP scopes (RAD-1074 required) and the threaded “NPis”
accessories on the input end. Requires either CWT-2070, STL-1071, or TRG-1072 to connect to camera.
5
STL-1071 – SBIG STL series camera adapter
• This adapter is sized to thread directly onto the STL series cameras and mates with Imaging System
accessories.
TRG-1072 – Standard T-ring adapter
• This is the most restrictive of adapters as it has the smallest inside diameter. Recommended for use
with APS size or smaller chips.
CWT-2070 – Canon Wide T Adapter
• Adapts Imaging System Accessories to Canon DSLRs. Includes Canon Bayonette mount.
• Eliminates the inner portion of Canon T-rings to provide a larger diameter opening for reduced vignetting.
AD2-1110 – Apogee U47-D2 Camera Adapter
A2A-1107 – 2” Accessory Adapter
• Use for cameras with 2” nosepiece or any other 2” accessory. (Extension tubes may be required to
reach focus.)
• Dual thumb-screws and clamp ring for positive locking.
AFT-1105 – 48mm Filter adapter
• Allows use of 48mm filters in the system.
• Best if used closest to the chip to minimize any vignetting
• Adds 0.25” of spacing.
TLA-0250 – 0.250” (6.4mm) Extension Tube
TLB-0375 – 0.375” (9.5mm) Extension Tube
TLC-0500 – 0.500” (12.7mm) Extension Tube
TLD-1000 – 1.000” (25.4mm) Extension Tube
TLF-0040 – 0.040” (1.0mm) Spacer
TLG-0080 – 0.080” (2.0mm) Spacer
TLS-1121 – Set of TLF-0040 and TLG-0080.
TLS-2245 – Set of all six.
• Threaded coupling provides the necessary distance for proper spacing of field lenses to chip.
Required spacers will vary depending on camera specifications.
• Black anodized aluminum with anti-reflection threads for maximum contrast.
Component Recommendations for Top Performance at Prime Focus
Recommended
Maximum
CCD/film
diagonal
Speed
Focal Length
Field of View
Camera
Connector
1
30mm
(APS size)
f/5.2
660mm
2.6°
T-ring
(TRG-1072)
or
Wide T-Ring
(CWT-2070)
X
X
2.375"
(2) TLD-1000
(1) TLB-0375
2
30mm
(APS size)
f/4.2
528mm
3.2°
T-ring
(TRG-1072)
or
Wide T-Ring
(CWT-2070)
X
0.8x Reducer
(NPR-1073)
0.5"
TLC-0500
3
40mm
(SBIG STL series
cameras)
f/5.2
660mm
SBIG STL Series
(STL-1071)
0.875"
(1) TLC-0500
(1) TLB0375
Large Field
Corrector
(LCL-1069)
1.5"
(1) TLD-1000
(1) TLC-0500
4
Apogee
Cameras with
D2 Lids
f/5.2
660mm
Will var y with
camera
1.250"
(1) TLD-1000
(1) TLA-0250
Large Field
Corrector
(LCL-1069)
1.375"
(1) TLD-1000
(1) TLB-0375
5
40mm
(35mm Film)
f/5.2
660mm
3.5°
0.25"
TLA-0250
Large Field
Corrector
(LCL-1069)
1.5"
(1) TLD-1000
(1) TLC-0500
Will var y with
camera
AD2-1110
T-ring
(TRG-1072)
or
Wide T-Ring
(CWT-2070)
6
Additional
spacer to match
Accessor y Lens
55mm
reference
Spacer length
from focuser
drawtube
4.1 Adjustable Position End Ring
The tilt of the End Ring to the optical axis can be changed to compensate for any tilt errors you may see
in your photography.
To determine which way to tilt the End Ring, it is necessary to focus on the part of the image that comes
to focus first when racking out the focuser from its “in” position. That will permit adjusting, or “jacking,”
the End Ring “out” to match that focus point in the field.
You will need to remove your camera equipment, including the Imaging System Adapter to adjust the
tilt of the End Ring . Slightly loosen the three Jamb Screws located on the face of the End Ring with the
appropriate Allen key. Then, “jack” the End Ring to the desired position using the appropriate Allen key
Jack Screws. Tighten the Jamb Screws against the End Ring and reinstall your camera. Some trial and
error imaging will be necessary, so it is best to carry out any necessary adjustment during an imaging
session.
4.2 Prime Focus
Prime focus photography involves attaching a camera, without its lens, to the telescope. In this method
the telescope becomes the camera’s lens. In the case of the NP127is, it is a 660mm focal length, f/5.2
telephoto. It is the focal length of the telescope in combination with the diagonal dimension of the CCD
chip or film frame that will determine the amount of field your photograph will cover. The shorter the focal
length or larger the diagonal dimension, the greater the field that will be recorded.
The parts necessary for Prime Focus photography are: camera with T-ring, appropriate T-ring adapter,
Extension Spacers, Imaging System adapter, telescope.
To obtain the best edge sharpness with CCD chips 30mm or larger, use the Large Field Corrector
(LCL-1069) in the configuration listed on page 6.
The recommendations in the chart and diagrams are specifically for SLR (digital or film), Apogee and
SBIG STL series cameras. If you have a different camera, you will need to determine the spacing necessary
to achieve reference distance from the seat of the Large Field Corrector to the CCD chip. These spacers
will be added between the seat of the Large Field Corrector and the face of your camera. Check the Tele
Vue website for on-going camera updates.
To start, you need to know the distance from the chip to the faceplate of the camera. This should
be specified in the camera’s documentation; call your camera’s manufacturer if it is not. The equation is
simply 2.6” ­— Chip to faceplate distance = additional spacer length required. There is enough tolerance
in this value that using threaded Imaging System extension tubes along with 0.040” and 0.080” spacers
to bring you as close as possible will work fine.
4.2a) To gain more field with chips APS size and smaller, use the 0.8x Reducer (NPR-1073). While the
reducer can be used with larger formats, noticeable vignetting will occur. The standard technique of “flat
fielding” should compensate. The arrangement of parts necessary for Prime Focus photography with the
0.8x Reducer is: camera with T-ring, appropriate T-ring adapter, NPR-1073, Extension Spacers to minimize draw tube out-travel, Imaging System adapter, telescope. The equation to figure the proper spacing
between the 0.8X Reducer and the CCD chip is: 2.44” ­— Chip to faceplate distance = additional spacer
length required.
4.2b) To gain more magnification, the 2x (PMT-2200) and 4x (PMT-4201) Powermates are recommended
for best performance. Start by inserting the 2” Accessory Adapter into the end of the focuser. (Since increasing the magnification will reduce the field, the large opening provided by the Imaging System Adapter is
of no benefit.) The arrangement of parts necessary is: camera with a T-ring attached, Powermate with corresponding T-ring adapter (PTR-2200 or PTR-4201) attached, 3.5” Extension Tube (X3C-0009), telescope.
There are certainly a variety of ways of setting up the Tele Vue-NP127is for photography!
7
5.0 Imaging System Focus Accessories
5.1 All Tele Vue telescopes with rack and pinion focusers
now permit the photographer to index focus position to
within 0.00005” by means of a digital indicator. Mounting points are provided on top of the focuser body and
end of the draw tube for easy installation of the various
Digital Indicator Kits. Using the Digital Indicator provides
a convenient way of finding best focus, returning to it,
or checking that it hasn’t changed.
Choose either the 10 Micron (0.0004”) Indicator
Kit (LMK-2404) or the 1 micron Indicator Kit (LMF-2405)
depending on the accuracy desired. Both indicators
have 0.5” motion ranges and accept an RS-232 output
cable for displaying readout on computer. The 10 foot
long RS-232 Output Cable (RSC-2320) permits remote
indicator readout on computer screen via downloadable
software from the Tele Vue website (www.TeleVue.com). The cable also provides power to the indicator.
5.2 The Focusmate Driver for the NP127is (FDF-2004) electronically drives the fine focus knob of the
Focusmate in steps of approximately 0.0005” per button click. With the button depressed, the motor
drives the Focusmate continuously without vibration transferred to the system. Motor speed is variable.
The motor has a standard phone jack that will accept a cord of any length. Remote control is possible.
Contact Tele Vue for further details.
5.3 The Tele Vue Imaging System comes full circle when you add the Focusmaster (FMU-2319) to your
system. The Focusmaster is the communication gate way for the Digital Indicator Kit and the Focusmate
Driver to become a “closed-loop” focusing system with your camera and camera control software. Converge focus quickly on the base of the “V” curve to within a micron when using our 1-micron indicator...
you just can’t do this by hand!
6.0 Caring for your NP127is
The Tele Vue-NP127is requires no special care. Treat it as you would any fine camera lens. Use the lens
cap when the telescope is being stored or not in use. The captive dew shield provides protection from glare,
helps protect the lens from dust or spray blown in by the wind and minimizes dew formation on the lens.
If dew forms on the lens during cold weather, it is best to use a hair dryer (on the lowest setting) to
gently warm it away. A few specks of dust will have no effect on image quality and may be gently blown
off with a squeeze bulb. Do not use compressed air cans to blow dust off optical surfaces.
Fingerprints, however should be cleaned off. Though the anti-reflection coatings are durable, they are
easily scratched. The simplest cleaning method is to moisten (not soak) a very soft, lint-free tissue, cloth,
“Q-Tip” or surgical cotton with a lens or glass cleaner and gently whisk away the stain. Do not apply
any solutions directly to the glass surfaces. After every cleaning stroke, use a fresh applicator. The fewer
strokes the better! Any residual “film” will not affect visual performance.
Collimation of your Tele Vue-NP127is has been locked at the factory. With reasonable care it will
remain aligned. However, rough handling can cause misalignment. WARNING: Do not loosen the button head screws in the front or rear lens cells as this will cause misalignment. If necessary, contact Tele
Vue for re-collimation.
The tube is powder-coated for durability and requires no special care. Black anodized surfaces can
be cleaned with Windex. If you have any questions about the care, operation or performance of your
Tele Vue-NP127is, please call us at (845) 469-4551 from 9:30 am to 5:00 pm EST.
8
7.0 Warranty
Tele Vue telescopes are warranted to be free of manufacturing or workmanship defects for 5 (five) years
from the date of purchase, to the original owner. Please return the warranty card as validation of your
ownership and for easy identification. If your Tele Vue telescope requires warranty service, please call
Tele Vue to discuss the problem, upon which you will receive a return authorization. NO RETURNS ARE
ACCEPTED WITHOUT PRIOR AUTHORIZATION.
The warranty does NOT include: collimation, defects caused by mishandling, defects of subjective
nature, or coverage for any telescope purchased through an unauthorized Tele Vue dealer.
Warranty work will be performed at Tele Vue’s discretion and may only be performed by Tele Vue
Optics. The telescope must be shipped in its case with proper inner and outer packaging. Return shipping
and insurance charges are the purchaser’s responsibility.
8.0 Specifications
Type 4-element, flat field, APO refractor, Fully Multi-Coated
Clear Aperture
5 inches (127mm)
Aperture Gain
329, compared to a 7mm exit pupil
Focal Length
660mm
Focal Ratio
f/5.2
Resolution (visual)
0.9 arc-sec. (Dawes Limit for a 5 inch aperture)
Resolution
277 line pairs per mm
(photographic)
Magnification 12x to 330x using Tele Vue eyepieces
Field, Visual
4o at 12x (55Pl) or 16x (41Pan)
Focuser
2.4-inch, rack and pinion type
Diagonal
Optional 2-inch 99% reflective dielectric coating, with 1¼” adapter
Finder
Optional Starbeam, Quick-Release Finder Bracket (50mm Finderscope not included), or low power eyepiece.
Mounting
Optional adjustable mount ring set with mounting plate for Gibraltar5 Mount
Weight
14.6 lbs. (tube assembly) 28 lbs. in case, 32 lbs. shipping
Length
33-inches (O.T.A. only)
Accessories
included as standard: custom fitted case, screw-on lens cover, sliding dew (glare) shield,
2” Accessory Adapter, Imaging Systems Adapter
TubePowder-coated aluminum
Specifications subject to change without notice.
9
Tele Vue recommends choosing low and medium power eyepieces in ratios of field stop diameters. For
example, factors of 1.4 or 2.0. When choosing higher power eyepieces, use ratios of magnification.
Tele Vue-NP127is
Focal
Length
(mm)
Type
Product Code
Apparent
Field (deg)
Weight
(lb.)
Mag.
True
Field
(deg)
Exit
Pupil
(mm)
# of
Elem.
Dioptrx
Ready
55
Plössl
EPL-55.0
50
46.0
41
Panoptic
EPO-41.0
68
46.0
38
1.1
12.0
3.99
10.6
4
Y
27
2.1
16.1
3.99
7.9
6
31
Nagler 5
EN5-31.0
82
Y
42.0
19
2.2
21.3
3.65
6.0
6
35
Panoptic
EPO-35.0
Y
68
38.7
24
1.6
18.9
3.36
6.7
6
21
Ethos
Y
ETH-21.0
100
36.2
15
2.3
31.4
3.14
4.0
-
26
Y
Nagler 5
EN5-26.0
82
35.0
16
1.6
25.4
3.04
5.0
6
Y
22
Nagler 4
EN4-22.0
82
31.1
19
1.5
30.0
2.70
4.2
7
Y
27
Panoptic
EPO-27.0
68
30.5
19
1.0
24.4
2.65
5.2
6
Y
17
Ethos
ETH-17.0
100
29.6
15
1.6
38.8
2.57
3.3
-
Y
20
Nagler 5
EN5-20.0
82
27.4
12
1.0
33.0
2.38
3.8
6
Y*
17
Nagler 4
EN4-17.0
82
24.3
17
1.6
38.8
2.11
3.3
7
Y
Y
Field Stop Dia.
(mm)
Eye Relief
(mm)
2" Eyepieces for Wide True Fields
1¼" Eyepieces for Wide True Fields
40
Plössl
EPL-40.0
43
27.0
28
0.4
16.5
2.34
7.7
4
32
Plössl
EPL-32.0
50
27.0
22
0.4
20.6
2.34
6.2
4
Y
24
Panoptic
EPO-24.0
68
27.0
15
0.5
27.5
2.34
4.6
6
Y*
13
Ethos
ETH-13.0
100
22.3
15
1.3
50.8
1.94
2.5
-
Y
16
Nagler 5
EN5-16.0
82
22.1
10
0.4
41.3
1.92
3.1
6
N
19
Panoptic
EPO-19.0
68
21.3
13
0.4
34.7
1.85
3.7
6
Y*
25
Plössl
EAP-25.0
50
21.2
17
0.3
26.4
1.84
4.8
4
N
17.3
Delos
EDL-17.3
72
21.2
20
0.9
38.2
1.84
3.3
-
Y
18.2
DeLite
EDE-18.2
62
19.1
20
0.5
36.3
1.66
3.5
-
Y
10
Ethos
ETH-10.0
100
17.7
15
1.1
66.0
1.54
1.9
-
Y
13
Nagler 6
EN6-13.0
82
17.6
12
0.4
50.8
1.53
2.5
7
Y*
14
Delos
EDL-14.0
72
17.3
20
0.9
47.1
1.50
2.7
-
Y
20
Plössl
EAP-20.0
50
17.1
14
0.2
33.0
1.48
3.8
4
N
12
Nagler 4
EN4-12.0
82
17.1
17
1.0
55.0
1.48
2.3
6
Y
12
Delos
EDL-12.0
72
15.0
20
0.9
55.0
1.30
2.3
-
Y
11
Nagler 6
EN6-11.0
82
14.9
12
0.4
60.0
1.29
2.1
7
Y*
10
Delos
EDL-10.0
72
12.7
20
0.9
66.0
1.10
1.9
-
Y
15
Plössl
EAP-15.0
50
12.6
10
0.2
44.0
1.09
2.9
4
N
Y*
1¼" Eyepieces for Medium Powers
9
Nagler 6
EN6-09.0
82
12.4
12
0.4
73.3
1.08
1.7
7
11
DeLite
EDE-11.0
62
11.7
20
0.4
60.0
1.02
2.1
-
Y
11
Plössl
EAP-11.0
50
9.1
8
0.1
60.0
0.79
2.1
4
N
8
Ethos
ETH-08.0
100
13.9
15
1.0
82.5
1.21
1.5
-
Y
6
Ethos
ETH-06.0
100
10.4
15
1.0
110.0
0.90
1.2
-
Y
8
Delos
EDL-08.0
72
9.9
20
1.0
82.5
0.86
1.5
-
Y
7
Nagler 6
EN6-07.0
82
9.7
12
0.5
94.3
0.84
1.3
7
Y*
4.7
Ethos SX
ETH-04.7
110
8.9
15
1.3
140.4
0.78
0.9
-
Y
6
Delos
EDL-06.0
72
7.6
20
1.0
110.0
0.66
1.2
-
Y
7
DeLite
EDE-07.0
62
7.5
20
0.5
94.3
0.65
1.3
-
Y
3.7
Ethos SX
ETH-03.7
110
7.0
15
1.1
178.4
0.61
0.7
-
Y
5
Nagler 6
EN6-05.0
82
7.0
12
0.5
132.0
0.61
1.0
7
Y*
N
1¼" Eyepieces for Higher Powers
8
Plössl
EAP-08.0
50
6.5
6
0.1
82.5
0.56
1.5
4
4.5
Delos
EDL-04.5
72
5.6
20
1.1
146.7
0.49
0.9
-
Y
3.5
Nagler 6
EN6-03.5
82
4.8
12
0.5
188.6
0.42
0.7
7
Y*
3.5
Delos
EDL-03.5
72
4.4
20
1.1
188.6
0.38
0.7
-
Y
2.5
Nagler 6
EN6-02.5
82
3.4
12
0.5
264.0
0.30
0.5
7
Y*
1¼" Zoom Eyepieces for Medium and Higher Powers
6-3
Nagler Zoom
ENZ-0306
50
5.1-2.6
NOTE: True Field in degrees = (Field Stop dia./Telescope Focal Length) X 57.3°
10
0.3
110.00.441.25
N
220.0
0.23
0.6
*Indicates additional Dioptrx Adapter required